Swift water rescuers say the help of Grantham residents was crucial as a flood disaster was unfolding in the town, west of Brisbane.

Ten days ago, the Lockyer Valley west of Brisbane was hit by a wall of water with no warning.

A number of people are dead or still missing.

Brad Mills and Andrew Neil are from the swift water team of the Queensland Fire and Rescue Service (QFRS).

They were the first on the ground in Grantham.

Mr Neil says the locals were a big help as the disaster was unfolding.

"We got one of them down next to the railway track with us to point out where the actual streets and everything were because at this stage there was just structures everywhere, just demolished," he said.

Mr Mills says they were not able to save everyone.

"Just the magnitude of it, the number of people, the situation," he said.